Inception

The dream-heist concept is executed with a confidence that a lot of imitators have never matched, and the practical effects (the folding city, the zero-gravity hallway fight) still look better than most CGI a decade later. The first act front-loads a lot of rule-explaining dialogue, which drags a bit, but once the team is inside the dream layers the movie earns its reputation. The ending is deliberately ambiguous and I liked that more than I expected to.